@article {SherringA143, author = {K Sherring and N Wilkinson and P Barton-Smith}, title = {349 Clear cell adenocarcinoma of the peritoneum arising on a background of endometriosis {\textendash} a rare case}, volume = {30}, number = {Suppl 3}, pages = {A143--A143}, year = {2020}, doi = {10.1136/ijgc-2020-IGCS.300}, publisher = {BMJ Specialist Journals}, abstract = {A 38 year old woman presented with a longstanding history of pain secondary to endometriosis. She had previously undergone major surgery with a segmental bowel resection seven years earlier. On assessment she was found to have a 3.7 cm right uterosacral ligament nodule with atypical appearances on transvaginal ultrasound scan. CA125 was 120 and risk of ovarian malignancy algorithm (ROMA) score was not suggestive of malignancy. A subsequent MRI scan, however, suggested suspicious findings. MDT discussion led to the decision to excise the mass along with a hysterectomy, bilateral salpingoophphorectomy and excision of pelvic endometriosis. Histology from the right uterosacral ligament nodule showed fragments of an adenocarcinoma with a tubulo-papillary architecture and hyalinised cores. The tumour cells were predominantly clear cells with some admixed eosinophilic cells, consistent with a clear cell carcinoma. There was no evidence of primary disease elsewhere within the gynaecological tract. The uterus was lined by proliferative endometrium and both ovaries contained foci of endometriosis but no evidence of atypia or carcinoma. There was extensive endometriosis throughout the remaining pelvic specimens but no further evidence of malignancy. The patient was referred to a tertiary centre for ongoing care and continues with this. Most recently she has suspected recurrent disease invading the right sacrum and pelvic nodes and is undergoing chemotherapy. Primary peritoneal clear cell carcinoma is rare, with only fourteen cases previously reported in the literature. Patients have been treated as per ovarian carcinoma with a variable response and it is considered to have a poor prognosis.}, issn = {1048-891X}, URL = {https://ijgc.bmj.com/content/30/Suppl_3/A143.1}, eprint = {https://ijgc.bmj.com/content/30/Suppl_3/A143.1.full.pdf}, journal = {International Journal of Gynecologic Cancer} }